Variations Among the Cary Audio CAD 211 Series Of Amps

So I have been looking at the possibility of a higher power tube amplifier based on transmitter tubes. Ideally I would like a SET based amp, but one of the options that keeps coming up is the Cary amplifiers. 

The 211M series has been around for awhile, and the cost of them varies a fair amount on the used market. 

Does anyone know the differences between the 211M and the 211M Anniversary Edition and if its significant enough to command a $2K price difference in the used market?

Also, what are your experiences with this series of amp in general, and how would you characterize their sonic signature?

Thanks for any info you can pass along.